1. Field of the Invention
The present invention relates in general to a plasma processing apparatus including a plasma generation mechanism, and more particularly to a plasma processing apparatus, such as a semiconductor manufacturing apparatus, which is suitable for the fine patterning of semiconductor devices.
2. Description of the Related Art
The fine patterning of the processing for semiconductor devices has made progress year by year, and as a result, the requirement for the size accuracy in the processing has been made more rigorous. On the other hand, in a plasma processing apparatus for generating the plasma operating on the process gases to process physically, chemically an object such as a semiconductor wafer, the reaction products generated in the inside of an apparatus chamber may adhere to the inner wall of the plasma chamber of the apparatus to remain thereon in some cases. Such reaction products within the chamber (vessel) change frequently the conditions of the processing for a wafer as an object of the processing. For this reason, as the processing for a wafer is repeatedly carried out any number of times, the conditions within the apparatus chamber exerting an influence on the processing are changed though the setting for the apparatus is held fixed, and as a result, the shape of the surface of the processed wafer, or the like is changed from the initial shape. Thus, there arises the problem that it is impossible to produce stably the objective semiconductor devices or the like.
In order to cope with the above-mentioned problem, there has been taken the measures in which the deposited materials on the inner wall of the chamber are removed by utilizing the plasma (cleaning), the temperature of the chamber wall is adjusted in order to make the deposited materials hardly adhere to the chamber wall, and so forth. However, the above-mentioned process conditions are changed until the removal of the deposited materials, and in addition thereto, it is difficult to remove the deposited materials to reduce sufficiently the change in state of the processing for wafers.
For this reason, the conditions of the apparatus and the processing state when the wafers are processed are gradually continued to be changed, and hence it is required for a user of the apparatus that the change in conditions of the apparatus and in processing state is detected before the change in processed shape has become the serious problem for the manufacture of the products, and then the plasma processing apparatus is decomposed to carry out the exchange of the parts and the cleaning using suitable liquid or a supersonic wave.
Furthermore, in addition to such deposited films adhering to the inside of the apparatus chamber, the fluctuation of the various factors such as the temperatures of the processing system takes part in the cause by which the apparatus conditions for the processing of wafers and the processing state fluctuate. In order to solve such a problem, there has been taken the measures of detecting the change in processing state in the inside of the plasma processing apparatus to carry out the cleaning depending on the detection result, or there has been made the device of feeding the detection result back to an input of the plasma processing apparatus to hold the processing state fixed.
One example of such a prior art is disclosed in JP-A-2001-60585 (prior art 1). This prior art 1 relates to a plasma etching apparatus which is designed in such a way that the electromagnetic radiation from the plasma within a chamber is measured through view ports formed in a sidewall, a top portion and a bottom portion of the chamber for the etching to transmit the measurement result to a process monitoring apparatus having a spectrometer and a processor through a fiber cable and the like. The process gases, the reaction products and a plurality of other plasmas are contained in the plasma within the chamber, and the electromagnetic radiation (luminous radiation) from the plasma within the chamber is measured by the spectrometer of the process monitoring apparatus to split the light from the plasma into a plurality of beams having different wavelengths which are in turn supplied to an array of a silicon charge coupled device. Then, it is possible to calculate the intensity of beam for each of the wavelengths using the outputs from the charged coupled device by the processor. As a result, it is possible to detect the information of the intensities of plural plasmas contained in the electromagnetic radiation. The above-mentioned contents are disclosed in the prior art 1.
In addition, the technique for detecting a plurality of beams having different wavelengths from such luminous radiation from the plasma within the chamber to analyze them is disclosed in JP-A-2002-5837 (prior art 2). The prior art 2 is such that it includes an optical detector having a plurality of charge coupled devices (CCDs) for subjecting the light from the plasma flame into the spectrum processing to obtain a plurality of beams having different wavelengths using a diffraction grating to detect a plurality of beams thus obtained after the spectrum processing, and the images of the beams having the different wavelengths are respectively imaged on the CCDs to analyze the quantities of elements, in the measurement components, differing in wavelength from one another using the intensities of the beams measured in the respective devices of the optical detector.